Unable to connect to the mongoDB using docker Kubernetes

Question

I am trying to connect to the default mongo image in Kubernetes, I am running Desktop docker for windows, below is the YAML configuration for the mongo service which I am using in the server code to connect.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: auth-mongo-depl
spec:
  replicas: 1
  selector:
    matchLabels:
      app: auth-mongo
  template:
    metadata:
      labels:
        app: auth-mongo
    spec:
      containers:
        - name: auth-mongo
          image: mongo
---
apiVersion: v1
kind: Service
metadata:
  name: auth-mongo-srv
spec:
  selector:
    app: auth-mongo
  ports:
    - name: db
      protocol: TCP
      port: 27017
      targetPort: 27107

Trying to connect to the Kubernetes instance through the below code

import express from 'express'
import { json } from 'body-parser'
import mongoose from 'mongoose'
const app = express()
app.use(json())

const start = async () => {
  console.log('Starting servers...!')
  try {
    await mongoose.connect('mongodb://auth-mongo-srv:27017/auth', {
      useNewUrlParser: true,
      useUnifiedTopology: true,
      useCreateIndex: true
    })
    console.log('Connected to MongoDB !')
  } catch (err) {
    console.log(err)
  }
  app.listen(3000, () => {
    console.log('Listening on port :3000 !')
  })
}

start()

Services and pods details

PS D:\auth> kubectl get service

NAME             TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)     AGE  
auth-mongo-srv   ClusterIP   10.103.93.74   <none>        27017/TCP   5h27m
auth-srv         ClusterIP   10.101.151.7   <none>        3000/TCP    5h27m
kubernetes       ClusterIP   10.96.0.1      <none>        443/TCP     17h  


PS D:\auth> kubectl get ep auth-mongo-srv 

NAME             ENDPOINTS         AGE
auth-mongo-srv   10.1.0.15:27107   5h28m

getting below errors

 MongooseServerSelectionError: connect ECONNREFUSED 10.103.93.74:27017
     at NativeConnection.Connection.openUri (/app/node_modules/mongoose/lib/connection.js:846:32)
     at /app/node_modules/mongoose/lib/index.js:351:10
     at /app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:32:5
     at new Promise (<anonymous>)
     at promiseOrCallback (/app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:31:10)
     at Mongoose._promiseOrCallback (/app/node_modules/mongoose/lib/index.js:1149:10)
     at Mongoose.connect (/app/node_modules/mongoose/lib/index.js:350:20)
     at /app/src/index.ts:28:20
     at step (/app/src/index.ts:33:23)
     at Object.next (/app/src/index.ts:14:53)
     at /app/src/index.ts:8:71
     at new Promise (<anonymous>)
     at __awaiter (/app/src/index.ts:4:12)
     at start (/app/src/index.ts:25:15)
     at Object.<anonymous> (/app/src/index.ts:43:1)
     at Module._compile (node:internal/modules/cjs/loader:1109:14) {
   reason: TopologyDescription {
     type: 'Single',
     setName: null,
     maxSetVersion: null,
     maxElectionId: null,
     servers: Map(1) { 'auth-mongo-srv:27017' => [ServerDescription] },
     stale: false,
     compatible: true,
     compatibilityError: null,
     logicalSessionTimeoutMinutes: null,
     heartbeatFrequencyMS: 10000,
     localThresholdMS: 15,
     commonWireVersion: null
   }

Do I need to run the Mongo DB service locally to connect to the Kubernetes mongo image? Below image is the Docker and Kubernetes versions.

Check the logs of your MongoDB pod. Also, I'm pretty sure you should use StatefulSet instead. — Riwen, Jun 09 '21 at 08:19
@Riwen, can you let me know where can I find the logs for the pods? I have updated the pods and services running status in the question have a look. — Rahul Gupta, Jun 09 '21 at 08:23
use the mongo db statefulsets image along with the open container port in deployment. ports: - containerPort: 27017 — Harsh Manvar, Jun 09 '21 at 09:06
The `targetPort:` in your Service is 27107, not 27017. Is that a copy-and-paste error in your question? It could cause this problem. — David Maze, Jun 09 '21 at 10:16
@DavidMaze, Thanks for pointing out that is the one that was causing the issue a simple typo issue. — Rahul Gupta, Jun 09 '21 at 13:40

score 0 · Answer 1 · answered Jun 09 '21 at 09:09

Please use the container port to in stateful set or deployment to open the port.

Deployment example :

apiVersion: v1
kind: Service
metadata:
  name: mongo
  labels:
    app: mongo
spec:
  type: LoadBalancer
  ports:
  - port: 27017
    name: http
  selector:
    app: mongo
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongo
  template:
    metadata:
      labels:
        app: mongo
        version: v1
    spec:
      containers:
        - name: mongo
          image: mongo:latest
          ports:
          - containerPort: 27017

statefulsets example :

apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
  name: mongo
  app: mongodb
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      terminationGracePeriodSeconds: 10
      containers:
        - name: mongo
          image: mongo
          command:
            - mongod
            - "--replSet"
            - rs0
            - "--smallfiles"
            - "--noprealloc"
          ports:
            - containerPort: 27017
          volumeMounts:
            - name: mongo-persistent-volume
              mountPath: /data/db
  volumeClaimTemplates:
  - metadata:
      name: mongo-persistent-volume
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 5Gi

here is an example statefulset for mongo db.

Unable to connect to the mongoDB using docker Kubernetes

1 Answers1